Six models leave Copilot on the same date
GitHub says Gemini 3.7 Flash, GPT-5.5, GPT-5.4, GPT-5.4 mini, GPT-5 mini and Grok 4.5 will be deprecated across GitHub Copilot on 19 October 2026. The change applies across Copilot Chat, inline edits, ask and agent modes and code completions rather than only the model picker in one client.
GitHub names direct replacement models
GitHub recommends Gemini 3.8 Flash for Gemini 3.7 Flash, GPT-5.6 Sol for GPT-5.5 and GPT-5.4, GPT-5.6 Luna for GPT-5.4 mini and GPT-5 mini, and Grok 4.6 for Grok 4.5. Workflows and integrations that explicitly request one of the retiring models need to be updated before the cutoff; GitHub says users do not need to take a separate action to remove the old models after deprecation.
Enterprise policy settings can affect the migration
For Copilot Business and Copilot Enterprise organisations using default model enablement, GitHub says the suggested alternatives are enabled automatically unless an administrator has disabled the global default or explicitly disabled a model. Organisations with the global default turned off may need to enable the replacement models through Copilot model policies before users can select them.
The deadline is about availability, not model equivalence
The changelog establishes the removal date, scope and GitHub's suggested substitutions. It does not claim that the replacement models reproduce the same latency, cost behaviour or output characteristics for every workload. Teams with model-specific prompts, evaluations or policy approvals therefore have one month from the announcement to test the replacement they intend to use before the old selection disappears.